About the lab
Our lab research is focused on nanomaterials preparation and characterization. Second topic are semiconductors.
Featured projects (1)
Featured research (6)
Reducing energy consumption during the hydrogen evolution reaction (HER) in the electrocatalytic water splitting for hydrogen production is still a challenge. Among the transition metal dichalcogenides (TMDs) family, platinum diselenide (PtSe2) exhibits good air stability, a low band-gap, and semimetallic properties, rendering it a promising catalyst for the HER. Herein, the selenization of predeposited Pt on reduced graphene oxide (rGO) substrate forming a 88 ± 6 nm PtSe2 thin layer, results in a free-standing, efficient HER electrocatalyst yielding a competitive performance in an alkaline medium, achieving a low overpotential of 95 mV at -10 mA cm−2. Furthermore, the PtSe2/rGO foil used in a two-electrode cell configuration demonstrates good long-term stability, up to 18 hours. The performance of the PtSe2/rGO foil results from the distribution of PtSe2 over the rGO substrate, which is maintained after the electrochemical reactions as attested by Raman mapping, and complemented by scanning electron microscopy (SEM), inductively coupled plasma optical emission spectrometry (ICP-OES), and X-ray photoelectron spectroscopy (XPS) characterization.
Promising applications of metal phosphorous trichalcogenides (M2P2X6 or MPX3) have been predicted in optoelectronics, photoelectrocatalysis, and water-splitting reactions, mainly due to its wide bandgap. Transition metals are widely used in the synthesis of MPX3, however, divalent cations of alkaline earth metals can also be constituents in MPX3 2D layered structures. Herein, MgPX3 (X = S, Se) are synthesized and their photoelectrochemical (PEC) activity is tested in the hydrogen evolution and oxygen evolution reaction (OER) regions under a wide range of wavelengths. MgPSe3 photoelectrode shows the best PEC performance with a response of 1.6 ± 0.1 mA cm−2 under 420 nm. In the light-assisted OER, a 200 mV improvement is obtained in the overpotential at 10 mA cm−2 for MgPSe3. The better performance of MgPSe3 is consistent with its lower optical bandgap (Eg = 3.15 eV), as a result of the variation of electronegativity between selenide and sulfide.
2D layered materials are currently one of the most explored materials in developing efficient and stable photoelectrocatalysts in energy conversion applications. Some of the 2D metal phosphorus chalcogenides (M2P2X6 or plainly MPX3) have been reported to be useful catalysts for water splitting. Herein, the photoresponsivity of a series of synthesized M2P2X6 (M2+ = Mn, Fe, Co, Zn, Cd; X = S, Se), tested for the oxygen evolution reaction (OER) region in alkaline media, with excitation wavelengths from 385 to 700 nm, is reported. The experimentally determined optical bandgaps of the MPX3 materials range from 1.5 eV for FePSe3 to 3.7 eV for ZnPS3. At +1.23 V versus reversible hydrogen electrode (RHE), the photoelectrochemical (PEC) activity in the OER region of MnPSe3 exhibits superior performance, while the exfoliation of CoPS3 improves its PEC activity up to double in contrast with its bulk counterpart. The influence of the substrate (glassy carbon (GC), indium tin oxide (ITO), and aluminum‐doped zinc oxide (AZO)) and applied potential is also studied. Exfoliated CoPS3 reaches a photoresponsivity of up to 0.6 mA W‐1 under 450 nm excitation wavelength and at +1.23 V versus RHE in alkaline electrolyte.
The advents in flexible and smart technology like wearable electronics have accelerated the demand for high-performance energy-storage devices. These devices could significantly reduce the size of the next-generation wearable smart electronics. A selection of suitable printing technology and its product typically offer a reasonable manufacturing pathway like high deposition rate, low materials waste, scalable fabrication, and high-performance production. Therefore, the production of novel functional inks with desirable rheological properties that authorize high-resolution printing, are some major challenges of this technology. This work has an emphasis on the recent advancements in supporting and utilizing liquid metals chemistry to synthesis high-quality and scalable 2D nanomaterials by liquid-phase free exfoliation and facile sonication-assisted methods. These are novel concepts in synthesizing 2D nanomaterials particularly for those which either have not intrinsic layered crystal structures or those with strong interaction between their crystal layers which are difficult to synthesized using conventional approaches. It also provides some potentials to make sustainable ink formulation of such 2D nanostructures for the fabrication of high-quality screen-printed patterns for sustainable energy applications. Subsequently, it deals with the possibilities and challenges of printing such 2D nanomaterials (namely, 2D metal oxides) for micro-supercapacitor and micro-battery applications on an industrially viable scale.
- Department of Inorganic Chemistry
About Zdenek Sofer
- Zdenek Sofer currently works at the Department of Inorganic Chemistry, University of Chemistry and Technology, Prague. Zdenek does research in Material Chemistry, Solid-state Chemistry and 2D materials. Their current project is focused on 2D materials.